Volume s1-26,
Issue 2,
1946

There can be no question that World War II has given to scientific research an impetus such as has never before been felt in the search for new knowledge and in its application. I need not review for this audience the events which have engendered such a widespread concern for the advance of scientific investigation. Suffice it to say that the developments of the war years have brought to science a wide popular recognition and a public interest hitherto unknown in the United States.

The prosecution of the war required that the Federal Government concern itself extensively with research and development of technological application of new scientific discoveries. This has been true in past wars as far back as the Civil War. The vast scope of global conflict and the evolutionary advance of science, however, have combined to increase the Government's rôle in research during the past six years to a stage which overshadows all previous activities.

Two new species of parasitic mites of the genus Neoschongastia, family Trombiculidae, namely, N. philippensis n.sp. and N. kohlsi n.sp. are described in this article. Both were taken from the ears of field rats, Rattus mindanensis mindanensis and R. vigoratus, indigenous to a focal area of scrub typhus in the vicinity of San Jose, Mindoro, Philippine Islands. The type specimens are deposited in the collections of the U. S. National Museum.

1.
Clinical data are presented on one small and 2 large outbreaks of scrub typhus which occurred in 3 different geographical locations in the SWPA and which showed variation in the severity of illness.

2.
Representative strains of the causative agent, Rickettsia orientalis were isolated in white mice from cases in the 3 areas and produced typical reactions in white mice, guinea pigs and rabbits.

3.
Strains isolated from cases in an outbreak with an extremely low mortality rate were less virulent for laboratory animals than strains isolated from cases in two other outbreaks with higher mortality rates.

From the results tabulated in this report the following conclusions may be made:

1.
The Bullis fever syndrome is a distinct clinical entity which may be reproduced in humans by the inoculation of blood from febrile cases of the disease.

2.
The Bullis fever agent from the blood of febrile cases has been propagated on the yolk sac of the developing chick embryo. Theyolk sac propagated agent reproduced the Bullis fever syndrome in humans after twenty serial transfers in the yolk sac.

3.
The Bullis fever agent has been isolated from tick emulsion (A. americanum) from Camp Bullis, and has been propagated in the yolk sac of the developing chick embryo. After the agent was propagated for twelve generations on the yolk sac of the developing chick embryo, it reproduced the Bullis fever syndrome in the human.

4.
The immunological responses induced by natural cases of disease by the blood propagated yolk sac strain and by the tick propagated yolk sac strain are the same.

5.
There is no immunological relationship between the agent of Bullis fever and the agent of Colorado tick fever.

1.
A filterable virus, believed to be hitherto unknown, has been isolated from Aedes mosquitoes caught in uninhabited forest in western Uganda. It has been provisionally named Bunyamwera virus in respect of the locality in which it was encountered.

2.
The agent is pathogenic for white mice and exerts its principal pathogenic effects on the nervous system regardless of the route by which it is introduced.

3.
The effects of the virus in rhesus monkeys and rabbits are discussed.

4.
The agent elicits the formation of virus-neutralizing antibodies in animals which survive inoculation. The presence of these antibodies may be ascertained by intracerebral or intraperitoneal tests.

5.
Bunyamwera virus is immunologically different from the viruses of yellow fever, Bwamba fever, St. Louis and Japanese B encephalitis, Rift Valley fever, eastern and western equine encephalomyelitis and horse-sickness, from West Nile and Semliki Forest viruses and from another neurotropic virus isolated here but not yet reported.

6.
Neutralizing antibody against the virus has been found in a forest monkey, in a human who suffered a recent attack of febrile illness characterized by marked neurological signs and in a number of persons sampled at random.

Evidence, in the form of 6 case reports, has been presented that algid malaria is due to the development of medical shock. This concept provides the clinician with a whole group of well recognized therapeutic aids for the treatment of a serious and often fatal illness.

INTRODUCTION Various methods of dissecting female anophelines to determine the presence or absence of oöcysts of plasmodia on the stomach and of sporozoites in the salivary glands are in use. Numerous descriptions of these procedures have been recorded in the literature, many being modifications of the method outlined in 1908 by Stephens and Christophers and later by Barber. Others who have contributed to this aspect of malariology include MacGregor, 1928; Craig, 1909; Boyd, 1930; Barber, 1930; Barraud, 1934; Missiroli, 1934; Russell and Baisas, 1935; Barber and Rice, 1936; Christophers and Covell, 1936; Wilcox and Logan, 1941; Covell, 1941; Simmons and Aitken, 1942; Puri, 1942; Blacklock and Wilson, 1942; Sevensson, 1943; and Geiman, 1944.

At the Army Medical School it has been necessary to teach mosquito dissection to large groups of individuals who have had little or no previous training in entomology. The size of the staff available for teaching this material has been limited.

1.
Cases of scrub typhus have occurred in troops during actions on the Islands of Leyte, Samar, Mindoro, Luzon, Negros and Mindanao. Japanese troops were reported to have encountered the disease on Mindanao. The largest epidemics occurred on Mindoro and Samar; widest distribution was encountered on Luzon.

2.
The clinical and laboratory findings were in agreement with previous military experience with this disease. The case fatality rate was 4.5 per cent.

3.
A strain of Rickettsia orientalis was recovered in laboratory mice from a patient on Samar and has been carried for 7 passages. Cross immunity with known strains of scrub typhus isolated in other geographic areas has been demonstrated.

4.
As in previous experience, environments where infections have been contracted have varied. Focal areas have been encountered in fields of the common Philippine grasses, “talahib” (Saccharum) and “kogan” (Imperator), as well as neglected coconut groves with scrub undergrowth overlying both sandy and corraline floors. Most infections were contracted at or just above beach levels but some came from mountain scrub areas as high as 3000 feet. (Outbreaks appeared to be more referrable to exigencies of military operations than to detectable seasonable influence.)

5.
Rats indigenous to focal areas have been identified as Rattus mindanensis, R. rattus umbrivenier and a small rat of the exulans group, R. vigoratus. The first appeared to be the most important mite host.

6.
Trombicula deliensis, a known mite vector was taken from rats of all the above islands except Leyte. The other proved vector, T. akamushi, was identified from rats on Luzon and Negros. Eight other species of mites have been found on Philippine rats.

7.
Incontrovertible evidence of the presence of tsutsugamushi disease (scrub typhus) in the Philippine Archipelago has been forthcoming for the first time during military operations on several islands in 1944–45.

Although chiggers are severe pests in many regions of the world and are important vectors of disease in a large area of the Far East, satisfactory rearing methods for these mites have not been found. Rearing is peculiarly important for disease transmission studies with chiggers, since an individual mite feeds on a vertebrate host but once during its entire life and in but one stage, the larva. The disease organisms must, therefore, pass from the larva of one generation through all successive stages, including the egg, to the larva of the next generation. While there has not yet been achieved the goal of carrying through the cycle from larva to larva without serious mortality, the method described below may serve as a basis for the development of a satisfactory technique. In its present form, however, the method has been of great value in studying all stages of the life cycle and in obtaining the taxonomically important nymphs and adults from larval chiggers.